To be honest i don't know what really happened, i just got this error after receiving some updates on the bot

System.NullReferenceException: Object reference not set to an instance of an object.
at TelegramBotBase.BotBase.Client_MessageLoop(Object sender, UpdateResult e)
at TelegramBotBase.Base.MessageClient.OnMessageLoop(UpdateResult update)
at TelegramBotBase.Base.MessageClient.HandleUpdateAsync(ITelegramBotClient botClient, Update update, CancellationToken cancellationToken)
at Telegram.Bot.Polling.DefaultUpdateHandler.HandleUpdateAsync(ITelegramBotClient botClient, Update update, CancellationToken cancellationToken)
at Telegram.Bot.Polling.DefaultUpdateReceiver.ReceiveAsync(IUpdateHandler updateHandler, CancellationToken cancellationToken)
at Telegram.Bot.TelegramBotClientExtensions.ReceiveAsync(ITelegramBotClient botClient, IUpdateHandler updateHandler, ReceiverOptions receiverOptions, CancellationToken cancellationToken)
at Telegram.Bot.TelegramBotClientExtensions.<>c__DisplayClass127_0.<b__0>d.MoveNext()

EDIT:

i ""fixed"" just by switching from the version 6.5 to 6.4